The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
One-to-one redundant power systems are often employed in present day Advanced TCA (Telecommunications Computing Architecture) (hereinafter “ATCA”) electronics equipment enclosures. Typically such enclosures make use of a plurality of shelves that each may support a plurality of “blades” (electronic printed circuit board modules) in side-by-side fashion. ATCA compliant enclosures typically have two power sources, and therefore use separate power entry modules (“PEMs”) in the electronics enclosure for each power source. One PEM is used for each power feed. Each power feed is formed by two cables: a power feed cable and a power return cable. The power feed and power return cables of a single power feed are coupled to a power branch within the enclosure. Each power branch within the enclosure is typically formed by a pair of power buses composed of a feed bus and a return bus that provide power to a subset of the blades in a particular shelf of the enclosure. Within the enclosure, after the PEMs, each power branch stays completely isolated from all the other power branches. The power branches of one PEM are thus all fully isolated from all of the other branches of other PEMs. Typically a redundant PEM or PEMs are employed with the enclosure and are coupled to separate power feed(s) from the other power source to form a backup power feed for a given branch within the enclosure.
With present day ATCA compliant enclosures, a PEM is used to interface each cabled power feed with a single power branch. Each power branch distributes power to one or more blades associated with the branch. “B” power branches distribute the power to the “M” blades per power branch. Within the PEM, the power feeds are connected to the power branches such that each power branch is driven from one and only one power feed. An example of such a typical present day configuration is shown in FIG. 1.
Although not shown in FIG. 1, typical ATCA compliant enclosures have shelves that include redundant PEM or PEMs and another set of power branch buses that drive each of the same blades in parallel to the power system diagrammed above. The power source is typically a −48 VDC battery bank, but the present disclosure is not limited to such cases.
With present day systems as shown in FIG. 1, an enclosure with four power branches per power source can have, for example, PEMs with: 1 power feed at 100 amps, 2 power feeds at 80 amps each, or 4 power feeds at 75 amps each. Because the power branches radiating outward from the power source cannot re-converge, there can be at most one power feed per branch. Thus, the single-feed PEM fans out its one power feed to the enclosure's four branches. Alternatively, the dual-feed PEM may fan out each of its two power feeds to two of the branches, and the quad-feed PEM directly connects each feed to only one power branch. Note that each PEM variant is required to drive all the power branches in the enclosure, or else some blades would receive no power. Presently, power feeds are limited to about 100 amps per cable set because of restrictions on the diameters of the cables that may be wired to a shelf of an ATCA compliant enclosure. The above limitations thus often find the system designer using a PEM or PEMs with a greater number of power feeds than what is needed for the power requirements of a given card configuration in an enclosure. This serves to increase the overall cost of the system. However, installing a PEM with only a single power feed connection to all the cards in the shelf may result in significant and costly work to reconfigure the enclosure in the event that the configuration of blades within the enclosure is changed at a later date.